JPH0726643Y2 - Plunger type length measuring device - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a plunger type length measuring instrument used for precise length measurement of a workpiece or a measurement target in a machine tool, a measuring instrument or the like.

[Conventional technology]

FIG. 3 is a sectional view showing an example of a conventional plunger type length measuring device.

A scale 2 having an optical grating is arranged in a hermetically sealed case 1. A slider portion 3 is mounted on which the surface of the scale 2 can be freely slid along the longitudinal direction by sandwiching the scale 2 therebetween. Although not shown, a detection unit is attached to the slider unit 3. A plunger 7 for measurement is provided through the case 1 via a sealing means such as an O-ring 6 so as to be slidable in the axial direction. One end of the plunger 7 in the case 1 is linked to the slider portion 3 by a drive shaft 5.

The plunger type length measuring instrument has a closed structure, so it is dustproof.
Excellent waterproof effect. However, when the plunger 7 is lengthened to increase the length measurement range and the diameter is increased to increase its rigidity, the deflection or vibration of the plunger 7 itself as shown by the broken line in FIG. There is a disadvantage in that the slider portion 3 is pulled up to the position of the broken line in the drawing due to the shake caused by the movement, and a measurement error occurs correspondingly.

In order to eliminate such an inconvenience, in the above-mentioned plunger type length measuring device, a sub-slider portion that moves via a guide means is provided in the case, and one end of the plunger in the case is connected to the sub-slider portion. The structure is used so that it is supported.

FIG. 4 is a sectional view showing an example of the connecting structure of the plunger and the sub-slider in the above-described length measuring device. A drive shaft 11 for interlockingly connecting the rod 10 and a slider (not shown) is connected to one end of the rod 10 inside the case (not shown) by a ball joint structure via a shaft retainer 12. A sub-slider receiver 14 is screwed into one end of the rod 10 via a disc spring 13 so that backlash does not occur in the ball joint structure of the shaft retainer 12. Then, a sub-slider 16 is mounted on the sub-slider receiver 14 via a disc spring 15, and the connecting slider 17 presses the sub-slider 16 against the sub-slider receiver 14 to connect the rod 10 and the sub-slider 16. .

FIG. 5 shows a structural example of another length measuring device having a sub-slider. A slider 20 movably provided on a scale in a case (not shown) is directly connected to a solid rod-shaped rod 22 via a drive shaft 21. The sub-slider 23, which moves along the slide guide in the case, is directly pressed against the rod 22 by using the disc spring 24 and the bush nut 25, and the rod 22 rotates with respect to the sub-slider 23. Are connected to each other.

[Problems to be solved by the device]

According to the length measuring device having the structure shown in FIG. 4, the connection between the rod 10 and the sub-slider 16 is fixed with respect to the rotational movement of the rod 10 and has no degree of freedom. The generated twisting motion of the rod 10 is directly transmitted to the sub-slider 16. Therefore, when the slide guide in the scale is slid, an undesired twisting force acts on the sub-slider 16, which adversely affects the scale accuracy and the scale life.

Further, according to the length measuring device having the structure shown in FIG.
Since it is not pipe-shaped and the signal line cannot be passed through the rod 22, the flexible cable 26 is arranged in the scale, and thereby the signal is output to the outside. Therefore, the flexible cable 26 accompanying the slide of the rod 22
However, there is a problem in that the bending motion of the product adversely affects the life and the reliability is reduced. In addition, there is a problem that a space for providing the flexible cable 26 and the like is required in the case, and the outer shape becomes large. There is also a problem that the cost of the flexible cable 26 is high.

[Means for Solving the Problems]

In the plunger type length measuring device of the present invention, the plunger that can move in and out of the case is supported by the sub-slider that is movable in the case, and the plunger that moves along the scale in the case can be used. In a plunger-type length measuring device interlockingly connected by a drive shaft, a tubular rod as a plunger, a rotary bearing fixed to one end of the rod inside the case, and a rotary bearing rotatably attached to the rotary bearing. A tubular rotary shaft that is held and has one end protruding from the rod and the rotary bearing, a connecting portion of the sub-slider that is attached using the one end of the rotary shaft as a guide, and one end of the rotary shaft. And a signal line wire-connected to the slider via the rod and the rotary shaft. It is.

[Action]

When the rod rotates, the rotary bearing that rotates together with the rod slides with respect to the connecting portion of the sub-slider that is pressed against the urging force of the spring member. Therefore, the rotational movement of the rod is not transmitted to the sub slider.

When the rod is bent, the spring member bends, causing a slip between the sub-slider connecting portion and the rotary bearing. Therefore, the bending movement of the rod is not transmitted to the sub slider.

The signal line from the slider, which is pulled out through the tubular rotary shaft and the rod, moves together with the sub-slider and the rod, so that no unreasonable force is applied to the signal line.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. 1 and 2. This embodiment relates to a plunger type length measuring device having a case having a closed structure, and in particular, here, a plunger that can freely move in and out of the case, and a sub-slider that supports one end of the plunger in the case are provided. The description will focus on the connection structure of.

The tubular rod 30 as a plunger is inserted into a sealed case (not shown) via a sealing member so as to be movable in the axial direction. As shown in FIG. 1, a cylindrical rotary bearing 31 is screwed and fixed to one open end of the rod 30 in the case. This rotary bearing
The flange 31 has a flange 32 that comes into contact with the open end surface of the rod 30, and an opening 33 that is narrowed like a nozzle.

As shown in FIG. 1, a tubular rotary shaft 35 having a guide hole 34 penetrating therethrough is rotatably held in the rotary bearing 31. The rotary shaft 35 has a tapered portion 36 having a shape matching the opening 33 of the rotary bearing 31, and a guide portion 37 protruding from the opening 33. Then, as shown in FIG. 2, a split groove 38 and a double chamfer 39 are formed on the outer peripheral surface of the guide portion 37.

A joint plate 41, which is a connecting portion of the sub-slider 40, is attached to the guide portion 37 of the rotating shaft 35. The inner diameter of the guide hole 42 provided in the joint plate 41 is slightly larger than the outer diameter of the guide portion 37. Also, this guide hole 42
A double chamfer 43 matching the double chamfer 39 of the guide portion 37 is formed on the. That is, the guide hole 42 of the joint plate 41
Double chamfer of guide part 37 of rotary shaft 35
When 39 is incorporated, the rotary shaft 35 and the joint plate 41 are interlocked only in the rotational direction, and even if the rotary shaft 35 moves in the bending direction, the motion is not transmitted to the joint plate 41. Although the joint plate 41 bolted to the sub-slider 40 is used as the interlocking portion of the sub-slider 40 in this embodiment, a part of the sub-slider 40 may be used as the connecting portion.

Rotating shaft inserted through the guide hole 42 of the joint plate 41
A joint spacer 45 having a notch 44, a disc spring 46 as a spring member, and a bush nut 47 for pressing the disc spring 46 are sequentially inserted into the guide portion 37 of the guide 35. A drive bearing 48 is screwed into the tip of the guide portion 37, holds the bush nut 47 in a state where the disc spring 46 is flexed, and rotates the joint plate 41 by the elastic force of the disc spring 46. It is configured to be pressed against the bearing 31. Further, a drive shaft 49 that connects the slider and the rod 30 (not shown) is incorporated in the drive bearing 48.

Although not shown, the slider connected to the rod 30 via the drive shaft 49 is provided with a detector. The signal line 50 from this detector is connected to the rotary shaft 35 from the split groove 38 of the rotary shaft 35.
Into the guide hole 34, is disposed in the central hole 51 of the rod 30, and is led out of the device from the other end of the rod 30.

The sub-slider 40, the rod 30 and the like connected as described above are housed in a case so as to be movable, the case is fixed to one of the two members to be measured which are relatively moving, and the rod is attached to the other member. Fix the other end of 30.

Depending on the attachment conditions of the rod 30 to the measurement target, the rod 30 may be subjected to rotational force or bending.

First, when the rod 30 receives a rotational force, the sub slider 40
Is guided by the guide means in the case, the sub-slider 40, the joint plate 41 and the rotary shaft 35 do not rotate. Then, the rotary bearing 31 that rotates together with the rod 30
A slip occurs on the joint plate 41 of the sub-slider 40, which is pressed by the biasing force of the disc spring 46.
Therefore, the rotational movement of the rod 30 is not transmitted to the sub-slider 40, and the signal line 50 is not twisted.

Next, when the rod 30 is bent, the disc spring 46 bends to cause a slip between the joint plate 41 of the sub-slider 40 and the rotary bearing 31. Therefore, the bending movement of the rod 30 is not transmitted to the sub slider 40.

Also, even if the rod 30, sub-slider 40, or slider of this device moves as the measurement target is driven, the center hole of the rod 30
Since the signal line 50 wiredly connected to the slider via 51 moves together with these, it does not receive any inconvenient external force.

[Effect of device]

In the plunger type length measuring device of the present invention, a rotating shaft fixed to a tubular rod holds a rotating shaft, and a connecting portion of a sub-slider guided by the rotating shaft is pressed against the rotating bearing by a spring member. It has a structure. Therefore, according to the present invention, the following effects can be obtained.

Since the rod is provided with the rotational degree of freedom and the bending degree of freedom at the connecting portion with the sub-slider, the twist or bending applied to the rod when the rod is attached and fixed to the object to be measured is not transmitted to the sub-slider. As a result, an unreasonable force is not applied when the sub-slider slides in the scale, the life of the device is significantly extended, and the measurement accuracy is improved.

Since the signal line from the slider can be passed through the inside of the rod, the flexible cable that repeatedly bends according to the movement of the slider in the case as in the past is no longer necessary, improving reliability and reducing cost. Can be lowered. Further, since it is not necessary to provide a space for disposing the flexible cable in the case, the outer shape of the device can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing an essential part of an embodiment of the present invention, FIG. 2 is an exploded perspective view showing an essential part of the same embodiment, and FIG. 3 is a sectional view showing an example of structure of a conventional plunger type length measuring device. FIG. 4 is a cross-sectional view showing a sub-slider connection structure in a conventional plunger type length measuring device, and FIG. 5 is a cross-sectional view showing another sub-slider connection structure in a conventional plunger type length measuring device. 30 ... Rod as plunger, 31 ... Rotating bearing, 35 ... Rotating shaft, 40 ... Sub-slider, 41 ... Joint plate as connecting part, 46 ... Disc spring as spring member, 50 ... Signal line.

Claims (1)

[Scope of utility model registration request] 1. A plunger, which is movable in and out of a case, is supported by a sub-slider, which is movable in the case, and is interlocked with a slider that moves along a scale in the case by a drive shaft. In the plunger type length measuring device, a tubular rod as a plunger, a rotary bearing fixed to one end of the rod inside the case, and rotatably held by the rotary bearing, A tubular rotary shaft having one end protruding from the rod and the rotary bearing, a connecting portion of the sub-slider that is attached using the one end of the rotary shaft as a guide, and the connecting shaft provided at one end of the rotary shaft. And a signal line wire-connected to the slider via the rod and the rotary shaft. Type length measuring device.